1. Field of the Invention
The present invention relates to an apparatus which visualizes an object to be measured (a measurement object) by utilizing a gamma ray source included in the measurement object. This technique is useful for visualizing a gamma ray source in a radioactive isotope handling apparatus and facility in the field of the nuclear fuel cycle (for example, enrichment, reprocessing, waste management/processing/disposal of nuclear fuel), and the like.
2. Description of the Related Art
There is an industrial X-ray CT scanner as an inspection apparatus which performs the imaging of the inside of a measurement object. The industrial X-ray CT scanner adopts a system in which an X-ray source outside the measurement object is needed to irradiate X-rays to the measurement object, so that a large-scale X-ray generator using a linear accelerator and the like is used. Therefore, an auxiliary apparatus such as an energy supply apparatus is needed for generating X-rays, as a result of which the industrial X-ray CT scanner as a whole is inevitably enlarged. Further, since the generation direction of X-rays and the X-ray detector need to be precisely positioned, the industrial X-ray CT scanner is assumed to be fixed and used. This leads to a restriction that the measurement object must be arranged so as to be movable. Further, the industrial X-ray CT scanner is constituted as a large-sized permanent facility, so that its maintenance is difficult to be performed.
As a technique which is capable of solving the above described problems, there is proposed an apparatus in which a radiation source is inserted in a heat exchanger tube to be inspected, and is utilized to image the cross section of the heat exchanger tube, so as to make it possible to easily and nondestructively perform inspection of defects and wall thickness of the tube, and the like (see Japanese Patent Laid-Open No. 2003-194740). However, this prior art is intended to perform the inspection of defects of the heat exchanger tube to be inspected itself, so that the cross section of the heat exchanger tube is imaged only by detecting the presence or absence of radiation. In this case, the radiation source is known and is inserted at the time of inspection, and hence, an operation such as to specify a nuclide is not needed. In such a technique, the analysis including specifying a radioactive nuclide cannot be effected, and need not be effected. Therefore, in this technique, it is impossible to discriminate a ray source nuclide and to measure concentration and spatial distribution of the ray source nuclide in the measurement object including a radiation source.